The present invention relates to devices for attaching, repairing or regenerating orthopedic tissue, particularly to such devices made from naturally occurring extracellular matrix cured or treated to have structural rigidity and hardness.
It is known to use various collagen scaffolds to provide a scaffold for repair and regeneration of damaged tissue. U.S. Pat. No. 6,042,610 to ReGen Biologics, hereby incorporated by reference, discloses the use of a device comprising a bioabsorbable material made at least in part from purified natural fibers. The purified natural fibers are cross-linked to form the device of U.S. Pat. No. 6,042,610. The device can be used to provide augmentation for a damaged meniscus. Related U.S. Pat. Nos. 5,735,903, 5,479,033, 5,306,311, 5,007,934, and 4,880,429 also disclose a meniscal augmentation device for establishing a scaffold adapted for ingrowth of meniscal fibrochondrocyts.
It is also known to use naturally occurring extracellular matrices (ECMs) to provide a scaffold for tissue repair and regeneration. One such ECM is small intestine submucosa (SIS). SIS has been described as a natural acellular biomaterial used to repair, support, and stabilize a wide variety of anatomical defects and traumatic injuries. See, for example, Cook® Online News Release provided by Cook Biotech Inc. at “www.cookgroup.com”. The SIS material is derived from porcine small intestinal submucosa that models the qualities of its host when implanted in human soft tissues. Further, it is taught that the SIS material provides a natural scaffold-like matrix with a three-dimensional structure and biochemical composition that attracts host cells and supports tissue remodeling. SIS products, such as OASIS and SURGISIS, are commercially available from Cook Biotech Inc., Bloomington, Ind.
Another SIS product, RESTORE Orthobiologic Implant, is available from DePuy Orthopaedics, Inc. in Warsaw, Ind. The DePuy product is described for use during rotator cuff surgery, and is provided as a resorbable framework that allows the rotator cuff tendon to regenerate. The RESTORE Implant is derived from porcine small intestine submucosa, a naturally occurring ECM (composed of mostly collagen type I (about 90% of dry weight) glycosaminoglycans and other biological molecules), that has been cleaned, disinfected, and sterilized. During seven years of preclinical testing in animals, there were no incidences of infection transmission from the implant to the host, and the RESTORE Implant has not adversely affected the systemic activity of the immune system.
While small intestine submucosa is available, other sources of ECM are known to be effective for tissue remodeling. These sources include, but are not limited to, stomach, bladder, alimentary, respiratory, or genital submucosa, or liver basement membrane. See, e.g., U.S. Pat. Nos. 6,379,710, 6,171,344, 6,099,567, and 5,554,389, hereby incorporated by reference. Further, while SIS is most often porcine derived, it is known that these various submucosa materials may be derived from non-porcine sources, including bovine and ovine sources. Additionally, the ECM material may also include partial layers of laminar muscularis mucosa, muscularis mucosa, lamina propria, stratum compactum and/or other tissue materials depending upon factors such as the source from which the ECM material was derived and the delamination procedure.
For the purposes of this invention, it is within the definition of a naturally occurring ECM to clean and/or comminute the ECM, or to cross-link the collagen within the ECM. It is also within the definition of naturally occurring extracellular matrix to fully or partially remove one or more components or subcomponents of the naturally occurring matrix. However, it is not within the definition of a naturally occurring ECM to extract, separate and purify the natural components or sub-components and reform a matrix material from purified natural components or sub-components. Also, while reference is made to SIS, it is understood that other naturally occurring ECMs (e.g., stomach, bladder, alimentary, respiratory or genital submucosa, and liver basement membrane), whatever the source (e.g., bovine, porcine, ovine) are within the scope of this invention. Thus, in this application, the terms “naturally occurring extracellular matrix” or “naturally occurring ECM” are intended to refer to extracellular matrix material that has been cleaned, disinfected, sterilized, and optionally cross-linked.
The following U.S. patents, hereby incorporated by reference, disclose the use of ECMs for the regeneration and repair of various tissues: U.S. Pat. Nos. 6,379,710; 6,187,039; 6,176,880; 6,126,686; 6,099,567; 6,096,347; 5,997,575; 5,993,844; 5,968,096; 5,955,110; 5,922,028; 5,885,619; 5,788,625; 5,762,966; 5,755,791; 5,753,267; 5,733,337; 5,711,969; 5,645,860; 5,641,518; 5,554,389; 5,516,533; 5,445,833; 5,372,821; 5,352,463; 5,281,422; and 5,275,826. U.S. Pat. No. 5,352,463 discloses an SIS pillow filled with comminuted SIS for regeneration of a meniscus. While U.S. Pat. No. 5,352,463 contemplates the general concept of meniscus regeneration with an SIS filled pouch, it does not address itself to providing such a pouch having the capability of withstanding the compression and shear stresses involved in an implant for regenerating a meniscus. Also, U.S. Pat. No. 5,352,463 does not contemplate placing structural members formed from naturally occurring ECM, where in the ECM is right and hardened.
It is known to use materials such as catgut and SIS to make appliances. See WO 95/06439 to Bolesky. The Bolesky application discloses devices that are semi-rigid and are formed into desired shapes, but Bolesky does not disclose a process for fabricating naturally occurring extracellular matrix parts that are rigid and hardened.
In the present invention, the density and porosity of the extracellular matrix material can be controlled with drying protocols, including air drying, air drying with heat, and air drying with pressure. Thus, the ECM material can be dried to have a hardness sufficient to machine the device, without the need to form the device into the general shape by molding. By managing density and porosity of the ECM, various fixation devices can be made having superior material properties, wherein the devices promote healing while remaining biocompatable and biodegradable.
The present invention, in one of its embodiments, is an orthopedic device for attaching soft tissue such as cartilage, ligaments, and tendons to bone. The device, which in one embodiment has a head end portion configured to engage soft tissue and a body portion configured to engage and attach to the bone, is preferably monolithic and formed as a unitary structure from naturally occurring extracellular matrix. The body portion of the device may illustratively terminate with a pointed end distal from the head portion to facilitate the penetration into the bone. Between the pointed distal end and the head portion, the device may illustratively be formed with radially outwardly extending barbs. These barbs may incline toward the head portion to provide a barbed tack or tack-like device. In some embodiments, a body portion is provided with diametrically opposed flats extending therealong, the flats being generally parallel.
It has been found that a mass of naturally occurring ECM may be cured to be very rigid and hardened so that it can be machined using conventional cutting tools and using laser machining. The devices of this invention may be formed by machining a mass of cured matrix to define the head portion and body portion. The mass may be formed by compressing the ECM into a solid mass. For example, the ECM may be comminuted and formed into a solid mass with interlocking strands of ECM.
For example, a tightly balled or compacted mass of pieces of SIS, illustratively comminuted SIS, can be formed by air drying or by hot air drying to become extremely hard. Unexpectedly, this hardened SIS can be machined or formed to have very sharp pointed ends, sharp barbs, etc. With this process, tacks, barbed tacks, and threaded elements may be machined from such cured mass of SIS. The tacks may be double-ended tacks or may include a central head portion and a sharpened body portion extending axially from each end of the head portion. Alternatively, a device may be made such that one body portion may be threaded while another body portion has barbs.
In one embodiment, such tacks or barbs may be attached to devices made of naturally occurring extracellular matrix laminated together to form a body portion. For example, such a body portion may be fabricated to be placed into the tear of a meniscus to extend along the tear. One or more tacks or barbs made in accordance with the present invention may be coupled to the body portion to secure the device in the tear. Each of these tacks may be made from naturally occurring extracellular matrix cured to be hard and rigid.
A staple or a staple-like device may be fabricated in accordance with the present invention utilizing two or more spaced apart barbs, each having a sharpened distal end and a proximal end. A connecting member may be placed between the proximal ends of the barbs. This connecting member may itself be made from a material such as SIS and optionally may be formed integrally with the barbs. Thus, in accordance with the present invention, an orthopedic staple device may be made from naturally occurring extracellular matrix hardened to have two or more sharpened barbs connected by strands of extracellular matrix such as SIS. In some embodiments of the present invention, such a staple or staple-like device may be made by laminating several layers of naturally occurring extracellular matrix and curing the layers to form a rigid and hardened sheet-like body. The barbs and the connecting member or members are then cut from the body. It has been found that the barbs and connecting member may be cut by laser machining a pattern on the sheet-like body. It has also been found that such barbs may be formed to have edges fused together by the laser machining process.
In another embodiment, a device for anchoring a bone plug in an opening formed in a bone is provided. The device comprises a mass of naturally occurring extracellular matrix formed into a rigid and hardened member configured to be wedged in the opening between the bone plug and the bone. This rigid and hardened member may be formed with outwardly extending barbs to dig into the bone plug and the bone. The device may also have a connecting portion to extend into an opening in the bone plug. In some embodiments, the member is designed to extend axially along side the bone plug, and the member may have a plurality of radially outwardly and longitudinally extending fins to dig into the bone plug and the bone. The elongated member may be cannulated so that it may be guided into place on a guide member such as a K-wire. In some embodiments, the member may be formed in the shape of a screw to be threaded into the opening between the bone plug and the bone.
There is provided, therefore, a method for anchoring a bone plug into an opening formed in a bone for receiving a plug, the method comprising the steps of providing a member formed into a rigid and hardened mass of naturally occurring extracellular matrix and placing the member into the opening between the bone and the bone plug. In some embodiments, the bone opening will be formed with a cylindrical wall and a bottom (or upper end) to receive a cylindrical bone plug, and the placing step will comprise placing the member in the bone plug to engage the bone plug and the bone. The member may be a double-ended tack, one end of which extends into the bottom of the opening and the other end of which extends into the bone plug. The double ended tack may radially expand the plug to engage the wall of the opening.
In another embodiment, a device for attaching a soft tissue such as a tendon, ligament, or ligament replacement has been provided. The device, which is formed from a hardened mass of naturally occurring extracellular matrix, is provided with an elongated body to be received in the opening in the bone. The body has a channel therein for receiving a portion of the soft tissue. This body is configured to collapse inwardly to grip and hold the soft tissue in the channel when the body is inserted into the opening. In some embodiments, the body may be threaded to accomplish inserting the device into the opening. It will be appreciated that such a device may be used for attaching an ACL replacement ligament in a tunnel formed in a femur, wherein the tunnel has an axis and a generally cylindrical wall. Such tunnel formation is known in the ACL replacement art. The body may be provided with a generally axial channel for receiving a portion of the ligament replacement to be attached to the femur, and the body may be formed to collapse inwardly to secure the replacement ligament portion in the channel as the device is threaded in the femur tunnel.
It will be appreciated that, in some embodiments, the naturally occurring extracellular matrix may be cured in such a fashion that the device will provide support structure members for various applications in the orthopedic field. For example, a device for regenerating a meniscus or a portion thereof may be provided with upper and lower panels and a support structure disposed between the upper and lower panels. This support structure may be provided by one or more members of rigid and hardened naturally occurring extracellular matrix. The one or more members may comprise a plurality of generally wedge-shaped members, each member having an upper edge supporting the upper panel and a lower edge supported on the lower panel. In other embodiments, the one or more support members may comprise a lattice of interlocking members, some of which extend radially toward the center of the knee and others of which extend transversely to the radially extending members. These members arranged in the lattice structure define a plurality of spaces between the upper and lower panel. These spaces may be filled with a biological material to promote regeneration of the meniscus. For example, the spaces may be filled with comminuted SIS, a bioactive agent, a biologically derived agent, cells, a biological lubricant, a biocompatible polymer, a biocompatible inorganic material, or combinations thereof. The ECM support structure is believed to provide a framework for meniscus generation. The insertion of the device into a space from which the defective portion of the meniscus has been removed and the attachment of the device to the surrounding tissue places the device such that the meniscus will be regenerated in the space from which the defective portion has been removed. The structural members provided by the rigid and hardened ECM will provide the required support for the joint while regeneration occurs. See U.S. Provisional Patent Application No. 60/305,786, and U.S. patent application Ser. No. 10/195,794 entitled “Meniscus Regeneration Device and Method” (Attorney Docket No. 265280-71141, DEP-745), filed concurrently herewith, each hereby incorporated by reference.
Thus, one aspect of this disclosure is an orthopedic device for attaching soft tissue such as cartilage, ligament and tendons to bone, the device having a head portion configured to engage soft tissue and a body portion configured to engage and attach to the bone, the head portion and body portion being monolithic and formed from naturally occurring extracellular matrix (ECM) cured to be rigid and hardened to facilitate attachment to the bone.
Another aspect of this disclosure is an orthopedic tack comprising a head portion and a first body portion formed from naturally occurring extracellular matrix cured to be hard and rigid.
Yet another aspect of this disclosure is a device for repairing a tear in a cartilaginous surface such as a meniscus, the device comprising strips of naturally occurring extracellular matrix laminated together to form a body portion to be placed down into the tear to extend along the tear, and one or more tacks coupled to the body portion to secure it in the tear, each of the one or more tacks being formed from naturally occurring extracellular matrix.
Still another aspect of this disclosure is an orthopedic device for attaching or repairing tissue, the device comprising two spaced apart barbs, each barb having a sharpened distal end and a proximal end, and a member connecting the proximal ends of the barbs, the barbs being formed from naturally occurring extracellular matrix
An additional aspect of this disclosure is a device for anchoring a bone plug in an opening formed in a bone, the device comprising a mass of naturally occurring extracellular matrix formed into a rigid and hardened member configured to be wedged in the opening between the bone plug and the bone.
Another additional aspect of this disclosure is a method for anchoring a bone plug into an opening formed in a bone for receiving the plug, the method comprising the steps of: providing a member formed into a rigid and hardened mass of naturally occurring extracellular matrix, and placing the member into the opening between the bone plug and the bone.
Still another aspect of this disclosure is a device for attaching a soft tissue to a bone that has been prepared with an opening to receive the device, the device being formed from a hardened mass of naturally occurring extracellular matrix to form an elongated body to be received in the opening, the body having a channel therein for receiving a portion of the soft tissue, the body being configured to collapse inwardly to grip and hold the soft tissue portion in the channel when the body is inserted into the opening.
A further aspect of this disclosure is a tack for driving into a bone, the tack having a proximal head end portion, a distal pointed end portion, and an intermediate body portion, the tack being formed from a hardened mass of naturally occurring extracellular matrix.
In yet another aspect of this disclosure a device is provided for regenerating a meniscus or a portion thereof, the device comprising a wedge-shaped body having an upper panel and a lower panel angularly separated to define an apex portion and a base portion, the panels being formed of a naturally occurring extracellular matrix, and a support structure disposed between the upper panel and lower panel, the support structure comprising one or more members of rigid and hardened naturally occurring extracellular matrix.
One more aspect of this disclosure is an orthopedic device comprising a mass of naturally occurring extracellular matrix or naturally occurring bioremodelable collagenous tissue matrix having a hardness greater than 30 HRD on the Rockwell D Scale.
A final aspect of this disclosure is a composite orthopedic device comprising two connected portions, each portion comprising naturally occurring extracellular matrix material or naturally occurring bioremodelable collagenous tissue matrix, each portion having a hardness and a density, wherein one portion is configured for anchoring the device to native tissue and has a hardness of no less than 50 HRD on the Rockwell D Scale and a density greater than 0.5 g/cc, and the other portion has a different configuration, a different hardness and a different density.